Template constraints should introduce identifiers inside their scopes

[HuskyNator]

On Wednesday, 21 September 2022 at 12:32:38 UTC, Paul Backus 
wrote:
> `static if` already handles these cases. I don't know exactly 
> what the rules are (needs better documentation), but presumably 
> they would work the same way for constraints.

Apologies, I only read your comment now.

> As I'm sure you're aware, there are cases where the desired 
> constraint cannot be expressed using template specializations. 
> For example:
>
> ```d
> auto fun(R)(R r)
>     if (isInputRange!R && is(ElementType!R == T[], T))
> ```

Thank you, this is indeed what I was aiming for :)